Liam Derbyshire was born with Ondine’s Curse, officially known as Congenital Central Hypoventilation Syndrome, which causes respiratory arrest due to a patient’s lungs not functioning when they are asleep.

The condition, which affects less than 1500 worldwide, means the 17-year-old has to be plugged into a life support machine and watched by a carer every night to keep him alive.

Doctors gave Liam just six weeks to live after birth, but later this year the young man from Gosport, South Hampshire, is turning 18 and has truly defied all odds.

Liam’s parents, Peter and Kim, act as a major part of his caring team and monitor their son 24 hours a day with specialised GPS equipment.

“You are constantly on the alert and you worry that perhaps it’s the last time you are saying good night.

“Liam’s sleeping arrangements are the electric bed which has three positions – it can be up or down and the head and feet can be lifted independently in order to give him some quality sleep.

“On the left hand side we have all of his ventilator equipment. The idea is that a ventilator supplies positive pressure so that Liam is actually forced to exhale CO2, which normally you or I would [naturally].

“There is also a plate under the mattress that will sense any sort of fitting and then the only way of making sure that he is still breathing is via that type of mask.

“Besides a medical room, it’s also his room and so you have got his PlayStation, the set TV and then Liam’s big forte – his Lego, which is all around the room.”

Liam also struggles with a bowel condition, something unrelated to Central Hyperventilation, which means he must eat substantially large portions of food throughout the day to keep his body functioning.

Kim said: “He lost a substantial part of his bowel when he was first born and now has an ileostomy bag, which he has had for many, many years.

“Food is a big issue for Liam. I have to plan every day and every way – the amount of food he goes through is quite terrifying.

“I have a budget given to me by my husband for food of around £800 a month but I would be lying if I didn’t say we actually spend more than that.

“It can be quite terrifying when people say how much I actually have to spend to keep my son alive. But I don’t have any choice.

“It’s imperative that he has drugs with whatever he is eating or he can begin to lose weight extremely quickly.”